Sheet feed apparatus



Nov. 14, 1967 R. GOSTENSEN 3,352,218

SHEET FEED APPARATUS Original Filed Jan. 5, 1963 5 Sheet-Sheet 1 IN V ENTOR.

z 2 BY RALPQ QOSTENSEN JM MQM Nov. 14, 1967 OSTENSEN SHEET FEEDAPPARATUS a sheets-Sheet 2 Original Filed Jan.

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Nov; 14, 196 7 R. G. OSTENSEN 3,352,218

SHEET FEED APPARATUS 3 Sheets-Sheet 5 Original Filed Jan.

INVENTOR. RALPH a O'iTENSEN United States Patent Office 3,352,218Patented Nov. 14, 1967 17 Claims. (Cl. 951.7)

This invention relates to duplicating apparatus and more particularly,to a photocopying apparatus having a copy paper feed system adapted tocontrol automatically movement of the copy sheet thereby requiring thatthe operator handle only the original document to be copied. Thisapplication is a division of my application Ser. No. 249,248 filed Jan.3, 1963, now abandoned.

A principal object of the present invention resides in providingapparatus for and a method of feeding the leading edge of a sheet ofcopy paper into a paper transport so that the copy sheet may be movedthrough the duplicating apparatus in timed relation with an originaldocument to be copied that is manually inserted into the document feedsystem of the apparatus.

Another object of the invention is to provide a novel copy paper feedarrangement for feeding the leading edge of the copy paper from thepaper supply compartment into the copy paper feed system. In thepreferred embodiment, this is accomplished by an intermittent paper feedwhich separates one sheet of copy paper at a time from a stack ofpre-cut copy paper and advances such separated sheet to a position wherethe further advancement of the sheet can be controlled with precision.When the original document is inserted in the apparatus, a switch isactuated by the leading edge of the document to thereby energize thecopy paper drive system. The original document and the copy sheet movein timed relation through an exposing station where a graphic image ofthe document is transferred to the copy sheet and the copy sheet thenadvanced through a developing station. While the exposed copy sheet isadvancing through the developing station, the leading edge of the nextsheet of copy paper is separated from the stack'of copy paper in thesupply compartment and advanced to the ready position at which time theapparatus is prepared to accept the next document to be copied.

Still another object resides in the provision of a novel single sheetseparator which enables the top sheet from a stack of pre-cut paper tobe fed singly into the copy paper drive transport of the copy apparatus.

Yet another object resides in providing a novel sequencing circuit foreffecting synchronization of the movement of the original or document tobe copied and the paper sheet together with a switching control toappropriately position the copy sheet part way through its feed systembefore the original is inserted.

These and other objects will become more fully apparent from the claims,and from, the description as it proceeds in connection with the drawingswherein:

FIGURE 1 is a perspective view as seen from the front, right corner ofthe electrostatic printer of the present invention shown with its coverin place;

FIGURE 2 is a sectional view of the printer of FIG- URE 1 and is takensubstantially along line 2-2 of that figure;

FIGURE 3 is a fragmentary view to an enlarged scale, of the copy sheetfeed means of FIGURE 2 and illustrates a novel arrangement for advancingsheets of copy paper singly through the printer;

FIGURE 4 is a perspective view as seen from the front, left corner ofthe printer of FIGURE 1 with the cover removed illustrating thearrangement and disposition of the internal components; and

FIGURE 5 is a schematic wiring diagram of the printer.

General description Referring now to FIGURES 1, 2 and 4, theelectrostatic printing machine 20 of the present invention including ahousing 22 within which are arranged a paper supply compartment 24 intowhich photoconductive copy paper stack 103.1nay be loaded and a paperfeed 26 for propelling sheets of the copy paper from compartment 24through a corona charging unit 27 where a uniform charge ofapproximately 400 v. is imparted to the surface of the copy paper toimaging area adjacent the lower end of an image projector 28. Theoriginal to be copied is inserted through a horizontal slot 30 in thefront wall 32 of cover 22 and is transported in timed relation to themovement of the copy paper to an imaging area below the forward end ofimage projector 28 where light is focused by projection lamp 36. Theimage is reflected from the surface of the original and a mirror 38 intothe objective lens 40 of image projector 28 which projects the imageonto the surface of the sheet of copy paper below corona unit 27. As theimage strikes the copy paper, the charge on the latter is reduced by anamount determined by the intensity of the reflected light, with blackportions of the original reflecting such a small light intensity as toaffect the charge very little and white portions of the originalreflecting sufficient light intensity as to almost completely releasethe latent electrostatic charge in the paper.

The exposed copy sheet now contains a latent image charge pattern whichis preferably passed through a developing tank 44, described in detailin my copending application 143,086 filed Oct. 5, 1961, now Patent No.3,202,526, where a liquid developer carrying positively chargedparticles is applied to the latent image bearing surface of the copypaper. The positively charged particles are attracted to the negativelycharged areas to a degree determined by the charge at each position onthe surface of the copy paper thereby producing a graphic image. Thepaper feed then moves the developed copy paper between squeegee rollers46 and 48, which remove the excess developer from the copy paper and mayprovide a direct voltage of relatively low magnitude to control the density of the image and/ or the cleanliness of the background of thedeveloped copy paper.

The radiant heat of the projection lamps, together with air warmed bythe projection lamps and blown across the copy paper by fans 50, removessubstantially all of the remaining moisture from the surface of the copypaper. Thereafter, feed system 26 deposits the copy paper onto surface52 at the bottom front of the printer from which it may be removed bythe operator.

Detailed description As is best shown in FIGURES 1 and 2, housing 22includes a base 54 supported on longitudinally extending feet 58 (onlyone of which is shown), a pair of spaced apart vertical side walls 60base, vertical front wall 32, which extends between the side walls, andrear wall 57. The details of housing 22 are of no significance to thepresent invention and'may be varied as desired. Side walls 60, forexample, are illustrated in FIGURE 2 as substantially continuous,sheetlike members. If desired, they may be formed of appropriate strapsor brackets since they function primarily to support various componentsof the printer such as the rollers for the copy paper and originaldocument feed systems shown best in FIGURE 4.

Supported on horizontal ledges 64 (FIGURE 1) formed adjacent the bottomof and extending around three sides of base 54 is a box-like open-endedcover 22 extending upwardly from the which may be secured in place byappropriate detachable fasteners (not shown). Louvers 68 formed in theexterior vertical side walls 70 of cover 22 permit cooling air to becirculated through printer 20 to remove the heat generated by itsoperation.

Paper feed system As is best shown in FIGURE 2, a copy paper supplycompartment 24 formed as a shallow sheet metal tray having bottom member78 is supported from the side walls 60. Copy paper may be loaded intocompartment 24 through the opening provided when hinged lid 76 in thetop wall 74 of cover 22 is opened.

The copy paper is withdrawn from the paper supply compartment by a pairof feed rollers 80 and 82 (see FIGURE 4) fixed on rotatable shaft 84which forms a part of paper feed 26. Shaft 84 is supported in parallelspaced relationship to a rotatable feed roller supporting shaft 86, andconnected thereto by drive belts 88 and 90. A pair of brackets (notshown) extend between shafts 84 and 86 and are pivotable about thelatter, thereby permitting feed rollers 80 and 82 to be displacedupwardly to the dotted line position shown in FIGURE 2 by openingmovement of door 76 when the latter is opened to load copy paper intocompartment 24. When door 76 is opened, horizontally extending pins 100fixed on arms 102 attached to the opposite sides of door 76 engage thelower runs of belts 88 and 90, raising feed rollers 80 and 82 to theposition shown in dotted lines. When door 76 is closed the feed rollersare lowered into engagement with the stack of copy paper identified byreference character 103.

As is shown in FIGURE 4, shaft 84 is driven by belts 88 and 90 whichextend around pulleys 92 and 94 fixed to the ends of shaft 84 and aroundpulleys 96 and 98 fixed to the ends of shaft 86. The weight of shaft 84,its rollers 80 and 82 and pulleys 92 and 94 is sufficient to provide thenecessary friction on the upper surface of the stack of paper 103 tocause the upper sheet to advance.

To insure proper functioning of printer 20', the sheets of copy papermust be fed one at a time from compartment 24. To prevent two sheetsfrom sticking together and passing simultaneously through the machine,the novel arrangement of cooperating guides 104 and 106 shown in FIGURE3 is employed. Guide 106 extends laterally of printer 20 substantiallythe width of the copy paper and is fastened by appropriate means to theside walls 60. Guide 106, which may be formed of sheet metal, has a mainflat body portion, a leading edge 108 that is upwardly inclined to guidethe top sheet of paper downwardly, and a horizontal rear edge portion110 joined by an upwardly and rearwardly inclined connecting portion112. The lower cooperating guide 104 is formed as an upwardly andrearwardly extending portion of bottom member of the paper loading tray78 which terminates with edge 105. Edge 105 is at about the level of thelower surface of section 106, is located below the lower surface ofsection 110 by a distance equal roughly to the thickness of two or threesheets of the copy paper 114 and 116, and is located from inclinedconnecting portion 112 by a distance sufficiently small so that thestiffness of paper sheet 114 provides a bias force at edge 105 toprevent the next lower sheet 116 from advancing until sheet 114 haspassed edge 105.

If two sheets of copy paper 114 and 116 advance to gether to be fedsimultaneously between guides 104 and 106, the top sheet 114 only willmove freely through the gap between the guides and on to rollers 118 and120 of the copy paper feed system. The leading edge of the bottom sheet116 will strike the upper surface of lower guide 104and be guidedupwardly. However, sheet 116 cannot advance beyond the edge 105 of guide104 until the trailing edge of the top sheet 114 has cleared lower guide104.

As was pointed out above, feed rollers 80 and 82 (FIGURE 4) of paperfeed 26 are driven by shaft 86 through belts 88 and 90. Shaft 86 isjournalled in suitable bearings (not shown) supported on the side walls60 of printer base 54. Fixed on shaft 86 is a feed roller 118 whichcooperates with a mating feed roller fixed on a shaft 122 to move thecopy paper through the printer. Shaft 122, like shaft 86, may berotatably mounted in suitable bearings supported from base side walls60.

Fixed to the ends of shafts 86 and 122, respectively, are a pair ofintermeshing spur gears 124 and 126, see FIGURE 4. Spur gear 126 is theoutput member of an electromagnetic clutch 128 which may be supported inany suitable manner on base side wall 60. The input member ofelectromagnetic clutch 128 is a spur gear 130 engaged by a roller chain132.

As is best shown in FIGURE 4, roller chain 132 is driven by a spur gear134 fixed to the output shaft of an electric driving motor 138 whichoperates continuously when printer 20 is energized. Therefore, whenelectromagnetic clutch 128 is energized a drive train will beestablished from drive motor 138 through roller chain 132,electromagnetic clutch 128, and spur gears 124 and 126, rotating feedrollers 118 and 120 in opposite directions to move a sheet of copy paperthrough them. With electromagnetic clutch 128 energized, a further drivetrain is established through pulleys 96 and 98 and belts 88 and 90 topulleys 92 and 94, rotating feed rollers 80 and 82 to withdraw copypaper from paper compartment 24 into feed rollers 118 and 120. Motor 138may be supported from base side walls 60 by appropriate brackets (notshown). A fan 139 fixed to the end of motor output shaft opposite spurgear 134 circulates air throughout the printer.

The next components in paper feed 26 are an idler roller 140 (seeFIGURES 2 and 4) over which the copy paper passes as it moves frombetween guide rollers 118 and 120 and a pair of guides 141 and 142between which the copy paper moves to a point where it is picked up byrollers 143 and 144. Idler roller 140 is fixed on a shaft rotatablysupported in appropriate bearings (not shown) fixed to base side walls60. Guides 141 and 142 may be formed from sheet metal and are supportedon base side walls 60. Idler roller 140 assists the copy paper in movingfreely between guides 141 and 142 to pick-up rollers 143 and 144.

Pick-up rollers 143 and 144 are mounted on shafts 147 and 158 rotatablysupported in bearings (not shown) fixed to base side walls 60. Pick-uproller 143 is continuously rotated by roller chain 132 which engages aspur gear 150 fixed to roller shaft 147. Roller 144 is driven by roller143.

Next in paper feed system are a pair of pick-up rollers 152 and 154,located below the charging electrodes of corona unit 27, similar to thefeed rollers 118 and 120 described above and rotatably supported frombase side walls 60 in the same manner as the latter. Roller 152 iscontinuously rotated by drive chain 132 via spur gear 156 fixed to theshaft on which roller 152 is mounted. Roller 152, in turn, frictionallydrives roller 154.

The next component in paper feed 26 is an endless conveyor 160whichincludes driven and driving rollers 162 and 164 rotatably supportedin parallel, spaced apart relationship by suitable bearings (not shown)fixed to base side walls 60. An endless conveyor belt 160 extendingaround rollers 162 and 164 maintains the copy paper flat while the imageof the original document is projected on it by imageprojector 28.

Conveyor belt 160 is continuously operated by roller chain 132 whichengages a spur gear 166 rotatably supported from base side wall 60. Spurgear 166 meshes with a spur gear 168 fixed to the end of the shaft 170on which driving roller 164 is mounted.

Endless conveyor 160 guides the copy paper to a pair of pick-up rollers172 and 174 which may be supported from the base side walls 60 in thesame manner as pickup rollers 152 and 154, for example. Roller 174 iscontinuously rotated by a spur gear 176 fixed to the end of endlessconveyor shaft 170 opposite spur gear 168. Spur gear 176 meshes with anidler gear 178 rotatably supported from base side wall 60. Idler gear178, in turn, meshes with and drives a spur gear 180 fixed adjacent theend of the shaft 182 on which roller 174 is mounted. Roller 174frictionally drives roller 172.

Disposed immediately below pick-up rollers 172 and 174 are a pair ofparallel, spaced apart sheet metal guides 184 and 186, see FIGURE 2,which are supported from base side walls 60 and between which the copypaper is guided into developing tank 44.

As the copy paper leaves developing tank 44, it is picked up and passedthrough squeegee rollers 46 and 48 which are rotatably supported frombase side walls 60 by suitable bearings (not shown). From the squeegeerollers the copy paper passes between a pair of spaced apart guides 187and 188, which are fastened to base side walls 60, into pick-up rollers189 and 190. Rollers 189 and 190 are rotatably journalled in suitablebearings (not shown) fixed to housing side walls 60. Roller 189 isdriven by roller chain 132 which engages a spur gear 191 fixed to theshaft 192 on which roller 189 is mounted. Roller 189 drives roller 190by friction and squeegee roller 48 by a drive train including a spurgear 193 fixed to the end of shaft 192 opposite spur gear 191. Spur gear193 meshes with an idler gear 194 supported in suitable .bearing (notshown) fixed to base side walls 60. Idler gear 194 meshes with a spurgear 195 fixed to the shaft 196 on which squeegee roller 48 is mounted.Squeegee roller 48 drives squeegee roller 46 by friction. From rollers189 and 190 the copy paper passes over a sheet metal guide 197 fastenedto the base side wall 60 onto the final component of paper feed 26, anendless conveyor 198 which includes a pair of parallel, spaced apartrollers 199 and 200 rotatably sup ported from base side wall 60. Loopedaround rollers 199 and 200 are a plurality of spaced apart cords 201which carry the copy paper downwardly and forwardly into a dischargetray surface 52. The spaced apart cords 201 permit air to be circulatedaround the exposed and developed copy paper to dry it.

Endless conveyor 198 is continuously driven by roller chain 132 whichengages a spur gear 202 fixed to a shaft 203 which is rotatablysupported from base side wall 60. Fixed on shaft 203 with spur gear 202is a spur gear 204 which meshes with a spur gear 205- fixed on shaft 206on which roller 200 is mounted.

As was pointed out above, paper feed 26, after withdrawing a sheet ofcopy paper from paper supply compartment 24, first feeds the sheet ofcopy paper through a corona unit 27 where a uniform charge ofapproximately 400 v. is imparted to its surface.

A satisfactory paper may consist of a coating of photo-' conductivematerial on a supporting base. The photoconductor is typically solidzinc oxide particles which are dispersed in a resin coating. The resinhas ahigh electrical resistance and may be selected from silicones,polyesters, styrene-butadiene copolymers and cellulose esters, and formsa smooth, uniform, highly adherent coating on the paper base. The papermay be made to have a charge When.

it leaves the corona unit on the order of 400 volts.

Image transfer Pick-up rollers 152 and 154 at the exit side of coronaunit 27, it will be remembered, deliver the charged copy paper onto thebelt of endless conveyor 160 where image projector 28 projects the imageof the document to be copied onto the copy paper. Image projector 28,which may be of substantially conventional construction, includes alight tight housing 269 with the objective lens 40 supported in itsupper forward end. A projection lens 270 is supported in the lowerrearward end of housing 269 closely adjacent the upper run of endlessconveyor 160. Image projector 28 is supported by a sheet metal supportmember 271 (see FIGURE 2) fixed at its opposite ends to base side walls60.

The original document which it is desired to copy, it will beremembered, is inserted into printer through a horizontal slot 30 in thefront wall of its housing 22 where it is picked up by the originaldocument feed 34. Referring now to FIGURES 1 and 4, feed 34 includes ahorizontal sheet metal guide 272 fixed to base side walls 60 whichguides the original into a pair of pick-up rollers 273 and 274 rotatablymounted in suitable bearings (not shown) fixed to base side walls 60.Roller 273 is continuously rotated by roller chain 132 which engages aspur gear 276 fixed to a shaft 278 rotatably supported on base side wall60. Fixed to shaft 278 with spur gear 276 is a second spur gear 280which meshes with a spur gear 282 fixed to the shaft 284 on which roller273 is mounted. Roller 2'74 is driven by roller 273.

The next components of document feed 34 are picka up rollers 286 and 288which are separated from pickup rollers 273 and 274 by a horizontallyextending sheet metal guide 289 supported by base side walls 60. Pick-uprollers 286 and 288 are rotatably mounted in suitable bearings (notshown) fixed to base side walls 60. Roller 288 is continuously rotatedby roller chain 132 which engages a spur gear 290 fixed to the end ofthe shaft 292 on which roller 288 is mounted. As in the other pick-uprollers described above, roller 288 frictionally drives roller 286.

Pick-up rollers 286 and 288 deliver the document to be copied onto anendless conveyor 294 which includes a pair of rollers 296 and 298rotatably journalled in parallel, spaced relationship by appropriatebearings (not shown) fixed to base side walls 60. Surrounding conveyorrollers 296 and 298 is an endless belt 300 which supports the documentto be copied while it is in the imaging area below the forward upper endof image projector 28. Endless conveyor belt 300 is driven by a spurgear 302 fixed to the end of the shaft 304 on which pick-up roller 286is mounted. Spur gear 302 meshes with a spur gear 306 fixed to the shaft308 on which endless conveyor roller 296 (see FIGURE 2) is mounted. Themovement of the document to be copied while on conveyor belt 300 issynchronized with movement of the copy sheet on conveyor belt by rollerchain 132 and the movement of the copy sheet is coordinated by use offeeler switches and electromagnetic clutches through a circuit shown inFIGURE 5.

As the leading edge of the document to be copied travels off the rearend of endless conveyor 294, it passes between a pair of pick-up rollers310 and 312 rotatably mounted in appropriate bearings (not shown) fixedto base side walls 60. Pick-up roller 310 is continuously rotated byroller chain 132 which engages a spur gear 314 rotatably supported byhousing side walls 60. Spur gear 314 meshes with spur gear 316 fixed tothe end of the shaft 318 on which roller 310' is mounted. Roller 310, inturn, friction drives roller 312.

Next in feed system 34 is a chute 320 formed from an arcuate wallportion 322 at the forward end of the support 271 on which imageprojector 28 is mounted and an arcuate sheet metal guide 324 supportedfrom base side Walls 60 in spaced, parallel relationship to support wallportion 322. Chute 3-20 diverts the document from its rearwardly movingtravel back toward the front of printer 20. As the document emerges fromchute 320, it passes beneath axially aligned and transversely spacedfeed rollers 326, 32-8, and 330 which deposit the document on a tray 332formed as an integral portion of the image projector supporting member271. Feed rollers 326, 328, and 330 are fixed on a continuously rotatingshaft 334 which is rotatably supported in appropriate bearings (notshown) fixed to housing side walls 60. Shaft 334 is rotated by rollerchain 132 which engages a spur gear 336 fixed to a stub shaft 338rotatably supported on housing side wall 60. Fixed on shaft 338 withspur gear 336 is a second spur gear 340 which meshes with a spur gear342 fixed on the end of roller supporting shaft 334.

As was pointed out above, it is the function of feed system 34 totransport the document to be copied to an imaging area below the upperforward end of image projector 28. In this area, the document to becopied is illuminated by projection lamp 36 which, as is shown inFIGURES 2 and 4, is mounted in a conventional parabolic reflector 344supported from housing side walls 60. The light from projection lamp 36reaches the document supported on endless belt 300 through a slit 346 ina sheet metal member 348 supported from base side walls 60 closelyadjacent and parallel to the upper run of endless conveyor 294.

It will be remembered that the image on the document is reflected fromits surface to a mirror 38. Mirror 38 is supported at an upwardly andrearwardly inclined angle adjacent the forward upper end of printerhousing 22 in a supporting bracket 350 fixed, at its ends, to base sideWalls 60. The details of mirror 38 and its supporting brackets 350 arenot critical in the practice of the present invention and may be of anycommercially available construction.

Mode of operation Referring now specifically to FIGURE 5, the operationof printer 20 is as follows: main on-off switch #9, which is mounted onthe front of printer base 54 (see also FIGURES 1 and 2), is closed.Connected in series with switch #9 are a pair of interlock switches #7and #8 mounted on printer base 54 (see FIGURE 2). Switches #7 and #8open when cover 22 is removed, preventing operation of the printerunless the cover is in place. With cover 22 in place safety switches #7and #8 are always closed and the closing of main switch #9 completescircuits through drive motor 138, a pump motor 358 in developing tank44, exhaust fans 50, and on-off lamps 360 mounted on the front ofprinter base 54 (see FIGURE 1), and electromagnetic clutch 128 throughnormally closed switch #3. Switch #3 is open when a sheet of copy paperis in position to start through corona charging unit 27.

The function of pump 358 is not germane to an understanding to thepresent invention, other than that it circulates a liquid developer ortoner solution which carries pigment particles that adhere to thecharged portion on the copy paper as it passes through the solution.This pump, the developer tank and their operation are described indetail in my copending application Ser. No. 143,086, now US. Patent No.3,202,526, to which reference may be had if desired.

Energization of fans 50, as was indicated above, effects a flow of airin printer 20 to remove the heat of operation from the printer and toassist in drying the developed copy paper after it leaves developer tank44 and passes through squeegee rollers 46 and 48.

Energization of drive motor 138 effects operation of the paper feeds 26and 34 described above. With drive motor 138 running and electromagneticclutch 128 energized, feed rollers 80 and 82 are rotated in a clockwisedirection as viewed in FIGURE 4, through the drive train describedabove, feeding a sheet of copy paper from stack 103 through the slotformed at the rear end of paper supply compartment 24 between guides 104and 106 to the pick-up rollers 118 and 120.

The sheet of copy paper passes through feed rollers 118 and 120, overidler roller 140, and between guides 141 and 142 until its leading edgeengages the actuator of a normally closed switch #3 and a normally openswitch #6, opening switch #3 and closing switch #6. Both of theseswitches are mounted on guide 142 (see FIGURE 4).

The opening of normally closed switch #3 interrupts the circuit toelectromagnetic clutch 128 which is then deenergized, stopping feedrollers 80 and 82 on top of the stack of copy paper and feed rollers 118and 120. The stopping of feed rollers 118 and 120 stops the sheet ofcopy paper passing through the printer with its leading edge just shortof pick-up rollers 143 and 144 insuring that, when a document to becopied is inserted into the machine, the document and copy paper willmove in timed relation through their respective imaging areas so thatthe entire image will be transmitted to the copy paper. The stopping offeed rollers and 82 insures that a second sheet of copy paper is not fedindiscriminately from supply compartment 24.

The closing of normally open switch #6 completes a circuit through areload-warning lamp 368 mounted on the front side of printer base 54(see FIGURE 1), lighting lamp 368 and indicating to the operator thatthe printer is conditioned to receive a document to be copied.

If the copy paper is exhausted when printer 20 is on, switch #6 will notclose and feed-reload lamp 368 will not light. Thus if lamp 368 does notlight within a few seconds after main switch #9 is closed, or after adocument is inserted through slot 30, the operator will know that thesupply of copy paper is exhausted. If this occurs main switch #9 may beopened, turning off the printer, and the supply of copy paperreplenished. Main switch #9 is then closed, relnitiating the printingcycle.

As the document to be copied is inserted through the slot 30 in printerbase front wall 32, it is picked up and fed into the printer bycontinuously rotating rollers 273 and 274. Shortly after it passesthrough rollers 273 and 274, the leading edge of the original contactsthe actuators of two normally open switches #1 and #5 mounted on guide289 with their actuators in the path of the inwardly moving original.

The closing of normally open switch #1 completes a circuit through athermal fuse 376 to the coil of a relay 378 energizing the relay whichcloses normally contacts 377. The closing of contacts 377 completes acircuit through and lights projection lamps 36 (which may be fixed inend-to-end relationship in reflector 344).

The closing of normally open relay contact 377 simultaneously completesa circuit through the primary of transformer 379. The secondary oftransformer 379 is connected in the high voltage circuit of corona 27which is nowhere grounded and therefore floats with respect to thereference voltage in the printer housing. For reasons which are notfully understood, it has been found that this arrangement preventsdiscoloration on the copy sheet which sometimes occurs when a groundconnection is used.

The DC. potential between the negative and positive output terminals ofvoltage doubler 380 is on the order of 11,500 volts.

The closing of normally open switch #5 completes a circuit through anormally closed switch #4 and again momentarily energizeselectromagnetic clutch 128 and causes rotation of feed rollers 118 and120 which move the sheet of copy paper downwardly between guides 141 and142 until its leading edge is engaged by continuously rotating pick-uprollers 143 and 144.

An instant after the leading edge of the sheet of copy paper is pickedup by rollers 143 and 144, its trailing edge clears feed rollers 118 and120. Simultaneously, the leading edge of the original opens normallyclosed switch #4 (which is mounted on guide 289 with its actuatorpositioned to be engaged by the rearwardly moving original),de-energizing electromagnetic clutch 128 and stopping feed rollers 80and 82 and feed rollers 118 and 120.

As pick-up rollers 143 and 144 move the sheet of copy paper downwardly,its trailing edge passes switches #3 and #6 permitting switch #6 to openand switch #3 to close. The opening of switch #6 extinguishes the feedreload warning lamp 368, warning the operator not to attempt to insertanother original into the printer. If an original were fed into theprinter at this point in the printing cycle, the original would precedethe copy paper through the imaging areas, producing an incomplete copy.

The closing of switch #3 again energizes electromag netic clutch 128,revolving feed rollers 80 and 82 in a clockwise direction and causingthe top sheet of copy sheet of copy paper in stack 103 to be fed out ofpaper supply compartment 24 between feed rollers 118 and 120. Shortlyafter the leading edge of this sheet of copy paper passes through thefeed rollers it engages the actuators of switches #3 and #6, openingswitch #3 and closing switch #6. Opening of switch #3 stops feed rollers118 and 120 positioning the incoming sheet of copy paper with itsleading edge slightly above feed rollers 143 and 144 so that, whenanother document to be copied is inserted into printer 20, the incomingcopy paper will be picked up and moved through the printer intimed'relation to the document in the manner described above.

The simultaneous closing of switch #6 relights feedreload lamp 368indicating to the operator that the printer is conditioned to receiveanother document to be copied.

It will be apparent, from the above discussions, that several sheets ofcopy paper may be moving simultaneously through printer 20, each of thesheets being at a diflerent stage in the printing cycle. Consequently,successive prints can be produced at a relatively rapid rate, on theorder of one copy every six seconds.

After moving through rollers 143 and 144, the sheet of copy paper whichtriggered the reloading cycle just described passes through corona unit27. As the paper moves through corona unit 27, uniform negative chargeis provided on the upper surface of the paper, and a similar positivecharge on the lower surface, the total charge being about 400 volts inthe illustrated embodiment.

The copy paper is a two layer system composed of a base which preferablyhas a resistance between approximately 50 and 500 megohms to the squareand a photoconductive layer or coating which may comprise aphotoconductive material such as zinc oxide in a resin binder.Therefore, when the copy paper leaves corona unit 27, the surface of thephotoconductive layer will be uniformly charged.

As the copy sheet emerges from corona unit 27, its leading edge ispicked up by rollers 152 and 154. Simultaneously, the leadin edge of theoriginal is picked up by rollers 286 and 288. Thereafter, the originaland the copy paper moves at the same speed to their respective imagingareas, the original passing from feed rollers 286 and 288 onto endlessconveyor 294 which carries it to the imaging area below the upperforward end Of image projector 28. The copy paper moves from rollers 152and 154 onto endless conveyor 160 which carries it to the imaging areaadjacentthe lower rear end of image projector 28. i

As the original document passes through its imaging area, it is struckby the light emitted from projection lamps 36 and focused on the imagingarea by parabolic reflector 344. The image on the document reflectedfrom the upper surface of the original to mirror 38 which reflects itinto the image projector 28 through objective 40.

The image passes through image projector 28, emerges through projectionlens 270, and strikes the negatively charged surface of the copy paper.The uniform negative charge on the copy paper is reduced in proportionto the intensity of the light striking the copy paper. Since littlelight will be reflected from the black areas of the original, the chargeon areas of the copy paper against which the light reflected from suchareas strikes will be reduced very slightly. On the other hand, thecharge on areas of the copy paper struck by the light reflected fromwhite areas of the original, such as the white background of a letter,e.g., will be almost entirely dissipated since the most intense lightwill be reflected from those areas.

As the original and the copy paper continue through their respectiveimaging areas, the image on the original is reproduced in latent form onthe copy paper through dissipation of the charge on its surface asdescribed above.

As the leading edge of the original emerges from its imaging area, itpasses off the end of endless conveyor 294 and is picked up by rollers310 and 312. Pick-up rollers 310 and 312 propel the original betweenguides 322 and 324 to feed rollers 326, 328, and 330 which deposit it intray 332 from which it may be removed and reinserted into the printer ofmultiple copies are desired. The originals are deposited face down intray 332. Therefore, if consecutively numbered originals are fed throughprinter 20, they will be deposited intray 332 in the same order.

Simultaneously, the leading edge of the exposed sheet of copy paperleaves the imaging area and is picked up by rollers 172 and 174 whichmove it toward developing tank 44.

As the leading edge of the copy paper emerges from rollers 172 and 174,it engages the actuator of and closes a normally open switch #2 mountedon guide 184 immediately below roller 174 as best seen in FIGURES 2 and4. Closing of switch #2 completes a holding circuit through relay coil378 as shown in FIGURE 8. Thus, when the trailing edge of the originalclears switch #1, permitting that switch to open, the projection lamps36 will not be prematurely extinguished. When the trailing edge of thecopy paper clears switch #2 (by which time the trailing edge of theoriginal will have cleared its imaging area) switch #2 will open,de-energizing relay 378. Upon relay coil 378 being de-energized, itscontacts 377 open turning off projection lamps 36 and opening thecircuit applying operating voltage to corona unit 27.

Development of latent image The developing tank 44 is located as closelyas practicable to the image forming area for the copy sheet at conveyorbelt 160. The copy paper is directed onto curved wire guide members 382shown in dotted lines in FIGURE 2 at the top central portion of tank 44.The liquid toner with electrostatically attractable particles is forcedthrough an apertured header 384 by the pump driven by pump motor 358 andapplied to the upper surface only of the copy paper. Suitableelectrostatic toners are well known in the art and include the examplesdescribed in United States Patent No. 3,001,888 to Metcalfe, et al., andin the Journal of Scientific Instrumerits, volume 32, February 1955,pages 74 and 75, In such toner solution the polarity of the charge onthe pigment particles can be controlled to be either negative orpositive.

In the embodiment described, it Will be assumed the pigment particleshave a positive charge and therefore will be attrached to image arealocations on the surface of the copy sheet that contain a negativecharge. The upper surface of the copy paper that passes beneath t eader384 in developer tank 44 has a negative charge distribution inaccordance with the electrostatic latent image to be developed. Theliquid applied to the upper surface runs off the sides of the paperwithout wetting the underneath side of the copy sheet as more fullydescribed in my copending application Ser. No. 143,086, now U.S. PatentNo. 3,202,526.

Any liquid adhering to the surface of the copy sheet is removed bysqueegee rollers 46 and 48, and runs back into the reservoir of toner intank 44. The copy paper then passes between rollers 189, 190 and intothe stream of heated air circulated by fans 50 across lamps 36 to removesuch moisture as remains on the copy sheet to thereby provide a nearlydry copy at surface 52.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The presentembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States LettersPatent is:

1. In a duplicating machine having means defining a storage compartmentcontaining photosensitive copy paper; means defining a copy paper travelpath including a first conveyor means, a copy paper image forming areaand a developing station; and means defining a document travel pathincluding .a document exposing area, which along with said copy paperimage forming area forms an exposing station; the combination of:

(a) means for advancing said copy paper from its storage position insaid storage compartment to said first conveyor means;

(b) means for stopping the advancing copy paper with its leading edge ata predetermined position between said storage compartment and said firstconveyor means;

(c) means for advancing a document to be copied along said documenttravel path and through saiddocument exposing zone;

(d) means responsive to the advancement of said document along saiddocument travel path to reinitiate movement of said copy paper to aposition when it is picked up by said first conveyor means foradvancement through said image forming area in timed relation withmovement of said document through said exposure area;

(e) means for moving said copy paper through said developing station;and

(f) said means for stopping the advancing copy paper comprising circuitmeans under the control of the copy paper during its movement past saidpredetermined position for rendering said copy paper advancing meansinoperative to advance the next sheet of stored copy paper to saidpredetermined position.

2. The duplicating machine as defined in claim 1 wherein the copy paperis supplied in the form of stacked sheets in said storage compartmenttogether with means for feeding the uppermost sheet one at a time fromsaid storage compartment into said copy paper travel path.

3. The duplicating machine as defined in claim 1 wherein said copy paperadvancing means is operated by said circuit means to advance the nextsheet of copy paper to said predetermined position only after thetrailing edge of the preceding sheet of copy paper clears saidpredetermined position.

4. The duplicating machine as defined in claim 1 comprising meansremotely located from said storage compartment outlet and providing forthe insertion of a document to be copied into said document travel path.

5. In an electrostatic printer having means defining a storagecompartment adapted to contain stacked photosensitive copy paper; meansdefining a copy paper travel path including seriatim a charging stationcapable of providing a substantially uniform charge on the copy paperwhile the copy paper moves through the charging station, a copy paperimage forming area and a developing station; and means defining adocument travel path including a document exposing area, which alongwith said copy paper image forming area forms an exposing station, thecombination of:

(a) means for advancing said copy paper from its storage position insaid storage compartment and along said copy paper travel path;

(b) means actuated by the copy paper advancing from said storagecompartment for stopping said copy paper with its leading edge at apredetermined position between said compartment and said image formingarea;

(c) means for advancing a document to be copied along said documenttravel path and through said document exposing zone;

(d) means responsive to the advancement of said document along saiddocument travel path to reinitiate movement of said copy paper foradvancement through said image forming area in timed relation with theadvancement of said document through said exposing area to enable thetransfer of an image from said document to said copy paper as thedocument and copy paper pass through their respective areas; and

(e) means for moving said copy sheet through said developing station;

(f) said means actuated by the advancing copy paper comprising switchmeans under the control of the copy paper during its movement past saidpredetermined position for rendering said copy paper advancing meansinoperative to advance the next sheet of copy paper to saidpredetermined position.

6. In an electrostatic printer having means defining a storagecompartment containing stacked sheets of cut photoconductive copy paper,means defining a copy sheet travel path including seriatim a chargingstation capable of providing a substantially uniform charge on the copysheet while the copy sheet moves through the charging station, a copysheet image forming area and a developing station, and means defining adocument travel path including a document exposing area, which alongwith said copy sheet image forming area forms an exposing station; thecombination of:

(a) means including intermittently driven rollers for advancing the topcopy sheet from said stack, one at a time through an outlet in saidstorage compartment and along said copy sheet travel path;

(b) means responsive to the advancement of the copy paper from saidstorage compartment for stopping said intermittently driven rollers toarrest the advancement of the copy paper with its leading edge at aposition that is intermediate said outlet and said charging station;

(c) means for advancing a document to be copied along said documenttravel path and through said document exposing area;

(d) continuously driven rollers spaced from said intermittently drivenrollers for advancing copy sheets through said charging station, saidcopy sheet image forming area, and said developing station; and

(e) means responsive to the movement of said document through apredetermined region along said document travel path for momentarilydriving said intermittently driven rollers to advance said copy sheetfrom said predetermined position to a position where it is picked up bysaid continuously driven rollers for advancement thereby through saidcopy sheet image forming area in timed relation with the advancement ofsaid document through said document exposing area to enable the transferof an image from said document to said copy paper as the document andcopy paper pass through their respective areas;

(f) said means for stopping said intermittently driven rollerscomprising circuit means under the control of the sheet of copy paper asit is advanced past said predetermined position by said continuouslydriven rollers for preventing operation of said intermittently drivenrollers after said intermittently driven rollers are momentarilyoperated by the movement of said document through said predeterminedregion.

7. In a copy machine: a copy paper supply means; first conveyor meansfor moving copy paper through a copy paper exposing zone; secondconveyor means for moving a document to be copied through a documentexposing zone in correlated relation to the passage of the copy paperthrough its exposing zone to effectuate transfer of the image on thedocument onto the copy paper; and third conveyor means for moving copypaper outwardly from the supply means to a rest position such that theleading edge of said copy paper is adjacent said first conveyor meansand thereafter for delivering said copy paper to said first conveyormeans when said document reaches a predetermined position along its pathof movement, for movement in correlated relation with the document to becopied, said third conveyor means comprising: a clutch means, a firstmicroswitch (#3) located at said predetermined position for stoppingsaid third conveyor means, second and third microswitches (#5 and #4)respectively actuatable sequentially by said document starting 'saidthird conveyor means to deliver said copy paper into said first conveyormeans and thereafter stopping said third conveyor means, the trailingedge of the copy sheet delivered into the first conveyor means beingeffective to activate said first microswitch to re-start said thirdconveyor means.

8. A device as defined in claim 7 wherein said supply means is acompartment, said copy paper and said document are each continuouslymoved across their respective exposing zones in time relation, saidfirst and second conveyor means are continuously operated and said thirdconveyor means is intermittently operated during machine operation, andsaid copy paper is a plurality of single stacked sheets adapted to beindividually sucessively fed through said copy machine.

9. The copy machine as defined in claim 7, including an operatorobservable feed-reload lamp and means actuated by arrival of a sheet ofcopy paper at the position adjacent the first conveyor means forcontrolling said lamp to indicate to the operator that the machine isconditioned to receive a document to be copied.

10. In an electrostatic printer, a copy paper supply compartment; a copypaper feed for moving copy paper from said compartment through anelectrostatic charging station, a copy paper exposing area, and adeveloping station to a first operator accessible depository; a documentpaper feed for moving a document to be copied through a documentexposing area and returning said document to a second operatoraccessible depository; said copy paper feed including an intermittentlyoperating portion for moving said copy paper from said supplycompartment to a point adjacent said charging station and a continuouslyoperating portion for moving said copy paper without pause through saidcharging station, said exposing area and said developing station to saidfirst depository; and means activated by movement of a document throughsaid document paper feed for initiating operation of said intermittentlyoperating portion to deliver said sheet of copy paper from theintermittently operating portion to the continuously operating portionof the copy paper feed.

11. The electrostatic printer as defined in claim 10 including anelectromagnetic clutch with its output connected in driving relationshipto the components of the intermittently operating portion of the copypaper feed, a continuously operating drive motor, and means driveconnecting said motor to the document paper feed, to the continuouslyoperating portion of the copy paper feed, and to the input of theelectromagnetic clutch.

12. In a copy machine: a copy paper supply compartment; first conveyormeans for moving a document to be copied through a document exposurezone; second conveyor means operated continuously with said firstconveyor means for moving sheets of copy paper one at a time through acopy paper exposure zone; intermittently operated conveyor means forwithdrawing sheets of copy paper one at a time from said supplycompartment and for stationarily positioning such withdrawn sheetadjacent to be spaced from said second conveyor means; and meansactuated by the document being advanced by said first conveyor means formomentarily driving said intermittently operated conveyor means todeliver said stationarily positioned sheet to said second conveyor meansfor movement by said second conveyor means through said copy paperexposure zone in timed relation with the movement of said document bysaid first conveyor means through said document exposure zone to therebyenable the transfer of an image from said document to the copy paper asthe document and copy paper are advanced through their respective zones.

13. In an electrostatic printer the combination of:

(a) a storage compartment for storing a stack of precut copy sheets;

(b) a first pair of intermittently operable rollers contiguous withtheupper surface of the top sheet of said stack;

(c) a lower guide means integral with the bottom wall of saidcompartmenthaving a horizontally extending bottom wall and an upwardlyinclined end portion;

(d) an upper guide means having a main body spaced above said lowerguide bottom wall and substantially parallel to said wall, an innerupwardly inclined end portion facing said stack, an outer end portionabove said lower guide end portion and substantially parallel to saidmain body portion and an upwardly inclined connecting portion disposedbetween said main body portion and said outer end portion andsubstantially parallel to said lower guide end portion;

(e) a seond pair of intermittently operable rollers disposed adjacentthe outer ends of said guide means and operatively connected to saidfirst intermittently operable rollers;

(f) an electromagnetic clutch for intermittently driving said first andsecond intermittently operable rollers;

(g) a first switch for disengaging said electromagnetic clutch when asheet of copy paper from said stack has moved to a predeterminedlocation;

(h) a first pair of continuously operable rollers having an entranceside disposed adjacent said predetermined location;

(i) a charging station adjacent the exit side to said first pair ofcontinuously operable rollers;

(j) an image forming station positioned to receive a charged copy paperfrom said charging station for forming a latent image thereon;

(k) a developing station positioned to receive a charged copy paper fromsaid charging station;

(1) a drying station positioned to receive said copy paper from saiddeveloping station;

(in) a first operator accessible depository positioned to receive saidcopy paper from said drying station;

(11) an original document inlet for insertion of a document to becopied;

(o) a second pair of continuously operable rollers;

(p) a second switch for energizing a radiation source;

(q) a third switch for engaging said electromagnetic clutch when saiddocument is advanced to a predetermined point so that said copy paper insaid predetermined location is advanced into said first pair ofcontinuously operable rollers to move in timed relation with saiddocument;

(r) an exposing station, positioned to receive said document from saidsecond pair of continuously operable rollers when said image formingstation receives said copy sheet, optically communicating with saidradiation source and said image forming station;

(s) a second operator accessible depository positioned to receive saiddocument from said exposing station.

14. In an electrostatic printer, a stack of sheets of copy 7 paper,first and second paper feeds for simultaneously transmitting a documentto be copied and a single sheet of copy paper through remotely locatedexposing areas, means including at least one source of projectionradiation for projecting the image on the document onto the copy paperas the document and copy paper pass through their respective exposingareas, means actuated by said document before it reaches its exposingarea for energizing said radiation source, and means actuated by saidcopy paper as its leading edge emerges from its exposing area forcompleting a holding circuit through said radiation source to maintainsaid radiation source energized until said copy sheet completely clearsits exposing area.

15. The electrostatic printer as defined in claim 14, wherein saiddocument actuated means includes a switch with its actuator disposed inthe path of movement of said document, said switch being closed by theleading edge of the document engaging said actuator and being opened bythe trailing edge of said document clearing said actuator.

16. The electrostatic printer as defined in claim 15, wherein said copypaper actuated means includes a switch with its actuator disposed in thepath of movement of said copy paper, said switch being of said paperengaging said actuator and being opened by the trailing edge of saidpaper clearing said actuator.

17. In a duplicating machine having copy paper and document exposurezones, means for advancing a document to be copied through said documentexposure zone, a copy paper storage compartment, first conveyor meansfor advancing sheets of copy paper through said copy paper exposurezone, second conveyor means for advancing the sheets of copy paperseriatim from said storage compartment to said first conveyor means,control means responsive to advancement of copy paper by said closed bythe leading edge second conveyor means for stopping said second conveyormeans to arrest the copy paper with its leading edge at a predeterminedposition between said storage compartment and said copy paper exposureZone, and means responsive to advancement of said document toward saiddocument exposure zone for momentarily re-actuating said second conveyormeans to advance said copy paper from said predetermined position to aposition where it is picked up by said first conveyor means foradvancement through said copy paper exposure zone in timed relation withthe movement of said document through said document exposure zone,thereby enabling the transfer of an image from said document to saidcopy paper as the copy paper and document pass through their respectivezones, said control means, following the momentary actuation of saidsecond conveyor means by the moving document, being responsive to thecopy paper being advanced by said first conveyor means to preventactuation of said second conveyor means until after the copy paperpasses beyond said predetermined position.

References Cited UNITED STATES PATENTS 2,153,154 4/1939 Nivison 27182,235,844 3/1941 Nelson 271-41 2,357,674 9/ 1944 McConnell 88-242,492,127 12/1949 Hessert 88--24 3,044,386 7/1962 Limberger 95-77.53,051,568 8/1962 Kaprelian 951.7 X 3,182,578 5/1965 Limberger 95--77.53,211,074 10/1965 Heiart 9577.5 X

JOHN M. HORAN, Primary Examiner;

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No.3,352,218 November 14, 1967 Ralph G. Ostensen It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

In the drawings, Sheet 1, Fig. 2, the reference numeral 386 and its leadline is deleted; same Fig. 2, the broken or dash lead line of referencenumeral 100 is extended to the lower left pin on arm 102; column 4, line46, for

"158" read 148 column 8, line 36, after "normally" insert open column 9,line 48, for "moves" read move line 60, after "document" insert iscolumn 10, line 13, for "of" read if line 27, for "FIGURE 8" read FIGURE5 line 58, for "attrached" read attracted column 13, line 29, for "time"read timed column 14, line 2, for "be" read but Signed and sealed this11th day of March 1969.

(SEAL) Attest:

EDWARD J. BRENNER EDWARD M.FLETCHER,JR.

Commissioner of Patents Attesting Officer

1. IN A DUPLICATING MACHINE HAVING MEANS DEFINING A STORAGE COMPARTMENTCONTAINING PHOTOSENSITIVE COPY PAPER; MEANS DEFINING A COPY PAPER TRAVELPATH INCLUDING A FIRST CONVEYOR MEANS, A COPY PAPER IMAGE FORMING AREAAND A DEVELOPING STATION; AND MEANS DEFINING A DOCUMENT TRAVEL PATHINCLUDING A DOCUMENT EXPOSING AREA, WHICH ALONG WITH SAID COPY PAPERIMAGE FORMING AREA FORMS AN EXPOSING STATION; THE COMBINATION OF: (A)MEANS FOR ADVANCING SAID COPY PAPER FROM ITS STORAGE POSITION IN SAIDSTORAGE COMPARTMENT TO SAID FIRST CONVEYOR MEANS; (B) MEANS FOR STOPPINGTHE ADVANCING COPY PAPER WITH ITS LEADING EDGE AT A PREDETERMINEDPOSITION BETWEEN SAID STORAGE COMPARTMENT AND SAID FRIST CONVEYOR MEANS;(C) MEANS FOR ADVANCING A DOCUMENT TO BE COPIED ALONG SAID DOCUMENTTRAVEL PATH AND THROUGH SAID DOCUMENT EXPOSING ZONE; (D) MEANS RESPONSIETO THE ADVANCEMENT OF SAID DOCUMENT ALONG SAID DOCUMENT TRAVEL PATH TOREINITIATE MOVEMENT OF SAID COPY PAPER TO A POSITION WHEN IT IS PICKEDUP BY SAID FIRST CONVEYOR MEANS FOR ADVANCEMENT THROUGH SAID IMAGEFORMING AREA IN TIMED RELATION WITH MOVEMENT OF SAID DOCUMENT THROUGHSAID EXPOSURE AREA; (E) MEANS FOR MOVING SAID COPY PAPER THROUGH SAIDDEVELOPING STATION; AND (F) SAID MEANS FOR STOPPING THE ADVANCING COPYPAPER COMPRISING CIRCUIT MEANS UNDER THE CONTROL OF THE COPY PAPERDURING ITS MOVEMENT PAST SAID PREDETERMINED POSITION FOR RENDERING SAIDCOPY PAPER ADVANCING MEANS INOPERATIVE TO ADVANCE THE NEXT SHEET OFSTORED COPY PAPER TO SAID PREDETERMINED POSITION.